Effects of non-Newtonian micropolar fluids on the squeeze-film characteristics between a sphere and a plate surface

On the basis of the Eringen's micro-continuum theory, this study is mainly concerned with the effects of non-Newtonian micropolar-fluid rheology on the squeeze-film characteristics between a sphere and a plate surface. To account for the micro-rotational effects and the micro-rotational inertia of the fluid elements arising from the lubricant blended with additives, the non-Newtonian Reynolds-type squeeze-film equation is derived using the continuity equation and the linear momentum equations coupled with the angular momentum equations. A closed-form solution for the film pressure, the load-carrying capacity and the time-height relationship is obtained for engineering applications. According to the results, the effects of non-Newtonian micropolar fluids provide an increase in the load capacity, and therefore lengthen the response time to prevent the contact of sphere with plate. Furthermore, the non-Newtonian effects on the squeeze-film characteristics are more emphasized under lower squeeze-film heights with larger coupling numbers and smaller interacting parameters. As the value of the coupling number tends to zero or the value of the interacting parameter approaches infinity, the presented derivation provides a close agreement with the Newtonian sphere-plate systems by Conway and Lee [1].